Washington — Donald Trump, the man to beat in this week's first televised Republican presidential debate, said on Sunday he does not plan to attack his rivals and downplayed expectations for his performance, saying "I'm not a debater."

The combative real estate mogul will take center stage at Thursday's debate among the 10 top-polling candidates as he leads the 17 Republicans competing to represent their party in the November 2016 election.

Trump has raised eyebrows and ire with attacks on his fellow candidates, accusing former Texas Governor Rick Perry of wearing glasses to look smarter and belittling the war hero status of U.S. Senator John McCain of Arizona, the party's 2008 presidential candidate and a prisoner during the Vietnam War.

"I don't think I'm going to be throwing punches. I'm not looking to attack them," he said on the ABC television program "This Week."

Trump said he had been viciously attacked by some of his rivals and that every attack he made was a "counter-punch."

"I think I'm a nice person, I really do," he said on NBC's "Meet the Press." "Frankly I'd like to discuss the issues. I am not looking to take anybody out or be nasty to anybody."

Recent polls show Trump sustaining his lead among Republicans, including former Florida Governor Jeb Bush and Wisconsin Governor Scott Walker, even after an outcry from within his party over the McCain comments.

The prime-time debate will feature the top 10 candidates in national polls. An earlier debate the same day will include the seven other candidates.

The set-up has drawn criticism, especially from candidates lagging in polls. Among them is former U.S. Senator Rick Santorum, the conservative who eked out a come-from-behind victory in the Iowa caucuses in the 2012 Republican contest. He criticized the Republican National Committee for agreeing to the terms of the debate.

"I guarantee you someone in that first debate is someone who's going to get a lot of delegates come next year and it'll be another instance when the RNC and the national media missed it," Santorum, of Pennsylvania, told ABC.

While no stranger to the national spotlight, Trump has never been in a political debate. He lowered expectations for his own performance while attacking his rivals for being better at debating than at getting things done.

"I'm not a debater," he said on ABC. "These politicians. I always say they're all talk, no action. They debate all the time ... I don't debate. I build."

Advisers for some candidates have said they will focus on the issues and try not to let Trump steal the show. Several said they would try to make a good impression on voters, rather than tangle with Trump.

"I have enough to do to get my message out to people," Ohio Governor John Kasich said on "Fox News Sunday."

He was asked about a tweet last week by political staffer John Weaver apparently aimed at Trump: "Imagine a NASCAR driver mentally preparing for a race knowing one of the drivers will be drunk. That's what prepping for this debate is like."

"He won't be sending any more tweets like that," Kasich said. "That's not the way we operate."

Trump said he was preparing for the debate but did not specify how.

"I don't think you can artificially prepare for something like this," he said on NBC. "I want to be me. I have to be me." (Reporting by Yeganeh Torbati, Timothy Gardner, Megan Cassell, Doina Chiacu; Writing by Doina Chiacu; Editing by Digby Lidstone, Toni Reinhold)